Dowelmax accuracy

[Craig Day]

Greetings all…

I am wondering what sort of accuracy everyone with a dowelmax is getting out if their alignment. I’ve had my dowelmax for a number of years now and accuracy has generally been decent, but my expectation is that the alignment is far better than what I’ve been getting. I have been very careful at edge alignment and using consistent clamping pressure but I am still sometimes what seems like almost 1/32” off in alignment.

I took the dowelmax to my mill with the DRO and my haimer 3D probe to measure the individual drill guide diameters, offsets from the edges/sides of the aluminum block they are installed in, and spacing between guides… I cannot fault the dowelmax nor the drill guides… it was surprisingly accurate and consistent between guides and from end-to-end/side-to-side… I’m not sure I seen a measurement more than a few tenths (.0001”) off.

So this leaves me to point to my drill bit itself and how tightly it fits in the drill guide. I am seeing a difference of about 0.008” between my drill bit and the drill guide. Even without taking a measurement there is noticeable slop. I am using a brad point bit so I get clean cuts going in… but I honestly don’t recall if this is the bit the dowelmax came with or not. The next thing I’d like to try is another drill bit that has a much tighter fit to the drill guides, but I feel like I’ll be rolling the dice here and just testing a bunch of bits that vary slightly around 0.375”.

So what sort of accuracy is everyone getting with their dowelmax? What sort of drill bits are you using and what sort of clearance do you have between the drill guide diameter and the drill bit diameter?

Is there something else I’m missing here with getting more accurate alignment?

cheers,
Craig

[John TenEyck]

0.008" doesn't explain how the joints would be off 0.032". A better fitting bit would help but there must be at least one other factor that's causing that much misalignment.

John

[Charles Lent]

The biggest error problem when using a Dowelmax is when the jig is not placed on the same side of the work pieces. You need to work and mark the face sides of all work pieces and reference your measurements only from the face side of the pieces. I've seen this several times when teaching students. Otherwise, the jig works very well. Did you forget to do this?

Charley

[Craig Day]

0.008" doesn't explain how the joints would be off 0.032". A better fitting bit would help but there must be at least one other factor that's causing that much misalignment.

John

Also my thoughts… I haven’t measured exactly how far I’m off… maybe it’s closer to 15-20 thou, but most definitely noticeable and aggravating…

If I don’t get any quick answers here then I’ll have to run some tests with different bits and experiment… so far I haven’t run any tests and just been dealing with the slightly inaccuracies… it was enough on my last project where I had to shave the dowels down on the mating side to get more play and allow precise alignment.

[Craig Day]

The biggest error problem when using a Dowelmax is when the jig is not placed on the same side of the work pieces. You need to work and mark the face sides of all work pieces and reference your measurements only from the face side of the pieces. I've seen this several times when teaching students. Otherwise, the jig works very well. Did you forget to do this?

Charley

Yes, I am very careful to check mark all mating surfaces/edges to match up with the marks on the dowelmax… so I’m pretty positive I’m doing that correctly. Sometimes my results are dead on, sometimes an unacceptable misalignment..

[Jim Mackell]

Greetings all…

… but I honestly don’t recall if this is the bit the dowelmax came with or not. The next thing I’d like to try is another drill bit that has a much tighter fit to the drill guides, but I feel like I’ll be rolling the dice here and just testing a bunch of bits that vary slightly around 0.375”.

cheers,
Craig

As I recall, the dowelmax did not come with a bit. The user supplies it. All my errors have been subtle misalignments on my part, usually due to sawdust buildup on my safety glasses

[Lisa Starr]

I don't use a DowelMax, but rather a Jessem that came with drill bits. I just checked and there is no slop between the bits and the bushings. I occasionally get misalignment, but it is always operator error. Either I inadvertently switch reference faces or I don't make sure there is no sawdust skewing the jig placement.